Ultrasound-assisted synthesis of layered zeolitic imidazolate framework: crystal formation and characteristics

Abstract

Two-dimensional (2-D) Zn/Co, Zn, and Co zeolitic imidazolium frameworks (ZIF) were synthesized using straightforward ultrasound techniques. Dual metal Zn/Co ZIF-L, Zn ZIF-L and Co ZIF-L with leaf-like shape morphologies were prepared in 15 min. Various characterizations have been applied including X-ray diffraction, scanning electron microscopy and energy dispersive X-ray photoelectron spectroscopy to verify that the 2-D structures of these ZIF-L series have been established. The influence of various synthetic conditions such as different metal/ligand ratios as well as different synthesis times on crystal structure, morphology and porosity of Zn/Co ZIF-L were investigated. Cross-leaf morphology was obtained by reducing the metal/ligand ratio. Study of CO₂ adsorption revealed that these ZIF-L series have a considerable CO₂ adsorption capacity. In situ fabrication of TiO₂ nanoparticles within Zn/Co ZIF-L was realized via ultrasonication for 15 min as Zn/Co ZIF-L was created. TiO₂@Zn/Co ZIF-L was effectively applied as a catalyst in photodegradation of methyl orange under solar irradiation. The results indicate that ultrasound is an efficient way to synthesize high-quality metal matrix frameworks (MOFs) and immobilize nanoparticles in MOF structures with high yield, in a short time.

Graphical Abstract

Keywords:

• Layered zeolitic imidazolium frameworks (ZIF-L)
• metal-organic framework (MOF)
• ultrasound technique
• TiO₂ nanoparticles
• photocatalysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support from the Shanghai Municipal Education Commission via the Oriental Scholar fund and the funding from the National Natural Science Foundation of China (NSFC) is acknowledged.